As integrated circuit devices incorporate more sophisticated and complex peripherals, there is a need for precise run-time control of an internal clock oscillator. For example, a USB 2.0 integrated peripheral must meet 0.25 percent clock frequency accuracy. A typical application would have to use an external crystal to control the clock frequency to that accuracy. However, an external crystal frequency determining device requires two integrated circuit pins for connection to the internal oscillator circuit in the integrated circuit device. This poses a problem for low pin count integrated circuit devices as two of the very few package pins must be dedicated for the external crystal.
An integrated circuit device oscillator using internal frequency determining elements would eliminate the external pins requirement for connection to a crystal. Such an oscillator having internal frequency determining elements, e.g., self contained oscillator, may be, for example but is not limited to, a resistor-capacitor (RC) oscillator. But a problem exists in that an internal self contained RC oscillator can drift in frequency even if it is precisely calibrated at the time of manufacture of the integrated circuit device. This drift may be attributed to package stress, fabrication soldering stress, temperature and/or voltage changes, etc.